1. Field of the Invention
The present invention pertains to protection devices for use with telecommunications equipment, and particularly to devices for protecting telecommunications equipment from potentially damaging current and voltage surges.
2. Description of the Related Art
Grounding mechanisms or devices are designed to protect telecommunications equipment from current surges and voltage surges by providing a grounding path in the event that either such event occurs. Grounding is necessary to prevent current and voltage surges from reaching and damaging fragile telecommunications equipment. Voltage surges typically result from lightning strikes which can generate voltages on the order of 20,000 volts.
A known solid state grounding device or protector 10 is depicted in FIGS. 1 and 2. The grounding protector 10 serves as an interface between an electronic module 12 having one or more diodes for connecting a tip wire 14 and a ring wire 16 to ground to allow the discharge of damaging voltage and current surges. The device 10 includes a pair of current sensors in the form of heat coils 18, 20, one for each of the tip and ring wires, respectively. The coils are mounted to a mounting base 32 and are biased in the downward direction relative to or toward the mounting base by tip spring 22 and ring spring 24. The heat coils 18 and 20 are maintained in an "up" or vertically offset position from the mounting base 32 by hardened solder lands or formations 30.
A leaf spring 26 is partially contained within a sleeve 28 that is mounted to module 12. The leaf spring is horizontally off-set or displaced from the tip and ring heat coils 18, 20 and is in physical and electrical contact with a module or diode clip 29 for providing a grounding path from the module 12 through the base 32 for voltage surges. Particularly, the leaf spring 26 contacts the diode clip 29 at a node 46 contained within a conducting region 38 (depicted in dashed lines in FIG. 2 and shown in detail in FIG. 3) and is supported, in part, by a grounding device housing 36.
In operation, and in the event of a current surge of relatively long duration through, for example, the tip wire 14, the solder land 30 on tip heat coil 18 will melt, allowing heat coil 18 to be displaced downward under the urgency of spring 22 into abutment with base 32 and thereby connect to a common ground through base 32. Since the module 12 is connected to both the tip and ring heating coils 18, 20, the assembly will tilt slightly in a direction of the movement of the heat coil.
In the event of a voltage surge such as from a lightning strike, the arc resulting therefrom will extend from the diode clip 29 to the leaf spring 26 through node 46 and be discharged to common ground through base 32. A problem that occurs, however, is that the arc will generate a force that pushes against the leaf spring 26, in the direction shown by arrow 34, thereby deflecting and permanently bending the leaf spring 26 away from diode clip 29, i.e. out of physical and possible electrical contact with module 12. This result renders the prior art grounding mechanism unable to defend against any subsequently occurring voltage and/or current surges, leaving the delicate telecommunications equipment connected through module 12 particularly susceptible to damage from such subsequently occurring surges.